Electric motor.



E F. W. ALEXANDERSON.

ELECTRIC MOTOR. A-PPLIOATION FILED JAN. 12, 1907.

Patented Apr.27,1909.

JfSZI/ENTUH .EHZYST F W ALEX N DEHSUZY.

WZTAEEES/ ATT'Y? UNITED STATES PATENTYOFFIGE;

ERINSIIF. w. lALEXAN nEasoN, OF SGHEN-EOTADY, NEW YORK; AssIeNoR 'ro GENERAL I ELECTRIC COMPANY, A CORPORATION OF NEWYORK.

ELECTRIC MOTOR.

Specification of Letters Patent.

Patented April 27, 1909'.

App1ioationfi1ed January 12, 1907. Serial No.,3'61,957.

' To all whom it'may concernfl its line on direct, and parton alternating current, to operate motors oneither kind of current; and as iswell known in the art, satisfactory operation with both kinds of current not easy to secure.

Be itknown that I, ERNST F. W. ALEX- ANnERsON, a citizen of the United States, re-- siding at Schenectady, count y-of Schenectady, State of New York, have invented cerprovide a novel method of adapting such motors for operation on both. direct and alternating-currents. I I I It'is oftendesirable, as, for instance, in the case of an electric railway operating part of Certain characteristics of the motor vary when changed from direct toalternating-current, or vice versa, so that a'motor which operates excellently on direct-current is not necessarily satisfac- One ofthese characteristics is the less satisfactory tory for alternating-current operation.

' commutation on alternating-current operaare advantageous for direct-current operation, due to the currents induced by the alternating field the coils 'short-circuited by the brushes. ,Another characteristic is the difference in field-strength required for operation on the two kinds of current. On account of the self-induction of the field when operated on alternating-current, it is undesirable to employ as many field turns as tion. I

My invention consists in taking advantage of each. of theabove characteristics to neutralize the other,or more specifically stated, in employing a portion of the COIlS which for'direct-current are used to produce the main field for producing a commutating I field for alternating-current Operation.

My invention further comprises. certain arran ements and connections of the'fieldv Figures 1 and) are explanatory diagrams, and Fig; 3 shows diagrammatically. a field winding of a motor and "commutating switch therefor adapted for carrying out mymethod of .controlin a simple manner.

' Referring first to Figs. 1 W12, A represents the armature, and B the brushes of a motor of the commutator type. .C represents a distributed compensating winding "carried on the field structure. I have chosen to illustrate this Winding as comepsed ofsingle conductors short-circuited y endrmgs. Thisls one well'known arrangement 'of compensatingwinding, and, as is'well' understood in the art, this Winding is effective only for alternating-current operation. If the winding is formed of coils connected in series with the armature, it is efiective'for both alternating and direct-current opera-.

tion;- but ordinarily,-sucha'winding is not required for direct-current, and thetype of winding illustrated is simpler. D represents the main fiel'd' coils of the motor. shown'a plurality of coils,'the coils of adjacent poles being separated by a tooth or lug d, which serves as a commutating polefoi' alternating-current operation.

If the relative directions of current in the conductors of thefield coils in the several slots for direct-current operation be considered, it will be seen that these directions will be as indicated by the plus and minus signs in Fig. 2. The direction of currentflow in all the coil conductors, in each slot is the same, so that all the coils assist in'pro- I have ducing the main field, and no magnetization I of the lugs d is produced. If it is desired to produce a commutating field in the lugs (Z, this may be accomplished by reversing the. direction of flow in a portion of the coil conductors 011 one side of each lug, as 'indicated by the plus and minus signs in Fig. 1. In this figure the coil conductors which lie adjacent to the tooth (Z produce the main field, as in Fig. 2, while the coil conductors more remote from' the tooth produce a magnetization of the tooth, which, if of the proper amount and phase may serve as a commutating field. For alternatingcurrent operation this commutating field is highly desirable, while for direct-current operation .it is not necessary. On the. other hand,

while all the field coils are required for the main magnetization, formost satisfactory direct-current operation, it is not desirabl ,upper slot may'beconnected to the lowest conductors in the right-hand slot to form atraced through coils D, D ,'D D, D and D all in series, to ground. When switch F is moved to its other position,'fone" terminal of coil D is left connected to coil- D. Coils D and D are left connected to 6 5 The relative reversal 1;;0 I.

-' tous'e all these-coils for the main magnetiza- 5.iield. Consequently, it the relative direc-'- tions of current-flow in the coil conductors are changed, as indicated by the,- plus and minus signs in Figs l and '2, respectively,

' when changing from alternating to direct current, the requirements 'for satisfactory operation with each kind of current, both with respect to the commutating field andthe number of main field turns, are satisfied.

In order to make the necessary change for I producing the relative reversal of currentflow-in a ortion of the field coils, the field coils shou d be properlyarrangedand con nected. By comparing the-coil conductors: V 2, it will be seen that the right-hand coil conductors alone are relatively reversed, and comparing in theupper slots in Figs. 1 and the coil conductors in the right-hand slots in thesefigures, it will be seenthat the low est conductors alone are reversed. Consequently, the right-hand conductors inthe I single coil, as indicated by the coil'D'Tin' Fig; 3! Similarly, the I upper coil conductors in the left-hand slot may be connected with the left-hand conductors in the lower; slot to:

I, iornranother coil D The remaining coil conductors may then be connected to form theremaining eoilsD to D". I

. 5 In Fig. 3 I have shown a switch suitably arranged for making the necessary changes in connections when shifting from direct to alternating-current, and vice versa-.' In this figure E' represents the. trolley or currentcollector, which 1nay at times be connected section, or vice versa. maln'iield coils. For dlrect-current' opera:

" tion, theleft-hand movable "contacts of switch F are brought into engagement with is then completed, which may readily be each other; the other terminal of coil .D 7 being connected .tothe .'unction of. coils D. and D the junctionfof'c now connected to ground.

' tion of current-fiow 'through coils Diand D -is reversed with respect of current in 't to a-sourceof direct current, and the others.

natingcurrent section, to" a direct e current.

.D represents the tion of said field the stationary contact-fingers, and a circuit.

' commutat'ing' ils I) itndfD being I Consequently, coils D. and D? are connected in" parallel with coils-D and D5, butthe relative direcf Im'ut-ator type having theothersix coils. the -direction oil-other coils at 'oneside thereof, and iL'SWii-C-ll I (3on9 and D -produces thejmagnetization' of the commutating lugs, while the parallel connection with coils D and D isfor the purpose of-securing in a simple manner, the

on the other Byproperly proportion'ing "the resistance G, this phase-displacement may be made ofthe proper amount for p r0- dueing the desired phase of the eommutatmg fiel a In Fig. 3', in order to. simplify the drawing, the armature "connections have been entirely omitted will be'understood that in the case of a series'motor, the armature would b'e co ected in seri'eswith the field circuit established by" the cornniutating switch --F. 1 In order to produce therelative reversal e propercoil conductors, in

forming the coilscertain of the coils--may overla certain; others .at one end. Byover apr I'meanthat these coils should ex. tend to the. far side-of one of the adjacent coinmutatinglu'gs, Thus, in Fig. 3 thecoils' D. and D? overla at one end, while th xcoils; D sand Disimilary overlap, 4 I'do not desire-tolirnit myself'to th'epar-v ticular 1 construction and; arrangement 1 of parts here shown, but, 'aimin the appended, claimsi "to l cover f all .modificatiens which are 'within the scope-of my invention. WhatlI claimasnew and desire to. secure I by. Letters Patent of the United States, is,- 1. The method of"oper 'ating-,a' motor of the" commutator type on both alternating meeting all the fieldl c'oils to assist in pro ducing the main field magnetization {for '10s I and direct-current,-which-consists in con- I operation on direct-current, and-for: alterhating-current operation employingfa porcoils for. producing a com mutating field.

.2, The niethodef operating ain otor oi the.

commutator. ype on both alternatingand direct-current, v which, consists in' femp yihg a portion of the field winding to producea fieldifor' f alternating-current operation, and employing said. portion to assistinproduc'ing the main fieldj magneti- 'zationfor direct-current"operation..-

"12o Incombinatiomamotoilofthe 'co1n mutatortype having a plurality of field coils.

per pole, a port on of said vcoilsoverlapp'in zot'hercolls at one side thereof and aswitch for reversing the j relative direction off our:

rent flow in a p'ortionof said field coils.

. 4. "In combination, a

.per pole,- a portion motor of the com-- I lurality of field'coils of said coils overlapping I i I i for reversing the relative dlrectlon of cur' said overlappi g muitator type having a plura ity of field coils iperpole, a magnetic tooth orlug separating the ield coils of adjacent poles, and a switch for reversing the relative direction of current-flow in a portion cffthe c'oil conductors on one side of said lugto produce therein a commutating' field.

6. In combination, a motor of the commutator type having a plurality of field coils per pole, a magnetic toothor lug separating the field coils of adjacent poles, a portion of said coils overlapping each other and having one side lying on the far side of one of the adjacent teeth, and a switch. for reversing the relative direction of-current-ilow in a portion of'said overlapping coils. v

7. In combination, amotor of the commutator type having a plurality of field coils per pole, a portion. of said 'coilsoverlappin other coils atone side thereof, and a switch for reversing the relative direction of ourrent-flow in one-half of said overlapping coils and connecting them inparallelfwith the other half.

8. In combination, a motor'of the com: nlutator type having a plurality of field coils per pole, a portion o'f'said coils overlapping other coils at one side thereof, a switohfor reversing the relative direction of current flow in onehall' of said overlapping coils and connecting them 1n parallel with the other held when changingfrom half, and means for controlling the relative phases of the currents in the parallel-com nected ,coils'. v i

9. In combination, a motor of the commutator type having a plurality oiiield coils per pole, a magnetic tooth. or lug separating the field coils of adjacent poles, a switch for reversing the relative direction of current-- flow in a portion of the coil conductors on one side of said lug to produce therein a co1rmutating field, and means for controlling the relative phase of the relatively-reversed current. X v I 10: In combination with a motor of the commutator type, means for supplying either direct or alternating-current thereto, and means for connecting a portion of the main field winding to produce a commutating field when changing from direct to alternating-current.

11. In combination with amotor' of the commutator type, means -for supplying either direct or alternating-current thereto,

means for connecting a portion of the main field winding to produce a commutating direct to alternating-current, and means for controlling the phase of the commutating field.

In witness whereof, I have hereunto set my hand this 10th day of January, 1907.

p I ERNST F. W. ALEXANDERSON. Witnesses:

BENJAMIN B. HULL, HELEN Onronn. 

